At present, the Third Generation Partnership Project (3GPP) is developing standards of Long Term Evolution (LTE) wireless communication systems. According to LTE, the use of techniques such as relay and carrier aggregation allows for an improvement in the maximum communication rate and an improvement in the quality at a cell edge. Also, attempts are being made to improve coverage by introducing base stations such as a Home eNodeB (HeNodeB), a femtocell base station, a small base station for mobile telephones), and a remote radio head (RHH), in addition to eNodeBs (macrocell base stations).
The 3GPP is also developing machine-type communications (MTC). MTC generally has the same meaning as that of machine-to-machine (M2M) communication, and means communication between machines that is not directly used by a human. MTC is mainly performed between a server and an MTC terminal that is not directly used by a human. MTC is believed to be an important elemental technology for efficiently connecting scattered apparatuses, such as a sensor network.
When LTE is applied to the above MTC, it is desirable that battery exchange for an MTC terminal be less frequent as possible. This is because battery exchange is a high-cost manual operation, and an MTC terminal may be installed at a place where battery exchange is difficult.
Incidentally, it is considered that, in the idle mode of LTE, the average power consumption of a terminal can be reduced by increasing a discontinuous reception (DRX) cycle, compared to the connection mode. Moreover, Patent Literature 1 and Patent Literature 2 describe improvements in paging technique.